Louver Damper,Adjustable,18H x 24W
5 In.5 In.H 26.W Drnbl Extrd Alu Combo Dmpr, Louver Type Combination, Frame Type Flanged, Outside Height 17 1/2 in, Outside Width 23 1/2 in, Rough Opening Height 18 in, Rough Opening Width 24 in, Louver Maximum Intake 1,090 cfm, Maximum Exhaust 1,559 cfm, Flange Width 1 1/2 in, Free Area 1 sq ft, Beginning Point of Water Penetration 1,118 fpm, Maximum Air Velocity 3,000 fpm, Blade Angle 45 Degrees , Material Aluminum, Inside Height 16 1/2 in, Inside Width 21 3/4 in, Number of Blades 3.